This invention relates to the field of molding systems and more particularly to an apparatus for reducing wear of the mold components and ejection system components.
The typical injection molding system contains a mold having a top half and a bottom half which are capable of being opened and closed during a molding cycle to create an article of manufacture. As is well known in the art, when the mold is closed, a material used to manufacture the article such as plastic, is injected into the mold where it is allowed to cool and set into its desired shape. Subsequently, the mold will open and the article will be ejected from the inside of the mold by an ejection system. The ejection system typically comprises one or more ejection plates having knockout pins and pushback pins affixed thereon. The knockout pins and pushback pins are oriented and sized to be insertable within bores when the ejection system is operating. After an article of manufacture has been cooled, the mold is opened and an ejection system press then pushes the ejection plates in a direction towards the mold plates. The pushback pins and knockout pins are inserted through the bores within the bottom plate. As the knockout pin is translated through its corresponding bore it contacts and forces the article of manufacture out of the mold. As the mold closes, the ejection plate is translated in the opposite direction such that the knockout pin is retracted towards its original position. The process is then repeated for each additional molding cycle.
Molding systems may weigh between 100 and 10,000 pounds depending upon the size of the article of manufacture. Accordingly, there is a substantial amount of friction associated with the knockout pins and pushback pins as they slide through the bores. This is particularly true if a mold is run in the horizontal direction because the weight of the ejection system is supported by the pushback pins. However, even molding systems run in a vertical direction are effected by friction and wear. A molding system may run continuously for days only to be stopped for repairs. Since repair of worn parts is often a lengthy and costly process, it is desireable to reduce the wear on the mold and ejection system components. By reducing wear the amount of molding time lost during down time necessary to effectuate repairs would be minimized thereby increasing productivity. Accordingly, the wear on the components of a molding system, particularly the pushback pins and knockout pins of ejection systems has been a longstanding problem in the molding art.
It is therefore an object of the present invention to create an apparatus which will reduce friction created by operation of a typical reciprocating ejection system.
It is also an object of the present invention to reduce wear on the ejection system components including knockout pins and pushback pins thereby increasing mold operation time.
It is also an object of the present invention to provide a system to reduce wear on an ejection system which may be used in either a vertical or horizontal position.